1. Field of the Invention
The present invention is a reinforced molding, for example a connector, such as a quick connector, suitable for use in a fuel-line system, particularly for use in an automobile. The reinforced molding of the present invention may be an injection-molded connector between plastic pipes (in particular those of fuel lines) as well as a molding used in other assemblies (e.g. injection rail, metal pipes, fuel filter, other plastic pipes or the like). Specifications for quick connectors are provided by SAE J2044.
2. Discussion of the Background
Generally, the flow of a substance over a plastic surface can cause a build-up of a static electrical charge on the plastic surface. Such plastic surfaces may include, for example, fuel lines in automobiles, and other types of plastic piping used to convey liquids and solids, and/or plastic components of piping used to convey liquids or solids. If the static electrical charge build-up is sufficiently great, sudden electrical discharges can result, which can cause various problems, such as degradation of the plastic surface, and/or ignition of the solids or liquids conveyed therein. For example, in internal combustion engine powered motor vehicles, high levels of static electrical charge arise in fuel-line systems as a result of the flow of fuel. This can lead to sudden electrical discharges resulting in the formation of perforations in the fuel-line wall, through which the fuel can escape. The fuel can then ignite if it contacts hot components within the engine compartment or the exhaust system, thereby causing a fire in the motor vehicle.
In order to avoid this problem, all of the components of the system, and therefore also the connectors, should be conductive. This requirement means that a conducting connection must first be provided between the individual components of the system, and second, a conducting connection must be provided between the system and an electrical xe2x80x9cground.xe2x80x9d In the case of an automotive fuel line, for example, an electrical connection should be maintained between the motor vehicle chassis and the components of the fuel-line system. In this way, the motor vehicle chassis and the components of the pipeline system are maintained at the same electrical potential, which prevents the build-up of electrical charge in the fuel-line system.
JP-A 207154/95 proposes producing connectors for fuel-line systems from a molding composition based on nylon-11 or nylon-12, in each case comprising from 5 to 20% by weight of carbon fibers and from 5 to 25% by weight of glass fibers. However, these molding compositions have poor flowability because of their high fiber content, which makes it considerably more difficult to produce small volume injection-molded items. These molding difficulties are further exacerbated if the mold has two or more cavities (i.e., molds used in producing fuel-line quick connectors). The longer flow paths in such molds make it even more important for the molding composition to have good flowability.
However, replacing the carbon fibers in the molding compositions of JP-A 207154/95 with a conductive black filler to improve the electrical conductivity of the molding eliminates some of the reinforcement in the composition, thereby weakening the molding. Furthermore, the amount of carbon black required generally increases the melt viscosity of the composition, which in turn adversely affects the filling of the cavity during injection molding. In addition, such compositions also exhibit lower impact strength.
A multi-layer structure is described in U.S. Pat. No. 5,798,048 for a plastic fuel filter housing. However, that publication does not relate to reinforced molding compositions, or with the problem of precisely reproducing finely structured surfaces from a mold.
The object of the present invention is therefore to provide plastic moldings such as connectors which are conductive and easily injection molded, and in which surface details, e.g. protrusions, recesses, grooves for O-rings, etc. can be reproduced with precision from the mold. At the same time, the molding should have sufficient fiber reinforcement to achieve the desired stiffness.
This object of the present invention may be achieved by a connector having a continuous conductive path from the inner to the outer surface and comprising:
A) a skin layer on the inner and outer surface of said molding, comprising an electrically conductive molding composition A; and
B) a core disposed between the skin layer on the inner and outer layer of said molding comprising a plastic molding composition B which differs from A.